The semi, which was heading west and carrying a load of large pipes, overturned about 4 miles east of Silverthorne. The truck missed using a runaway truck ramp, and the pipe spilled into the eastbound lanes, said Tracy Trulove, a CDOT spokeswoman.

A pickup was forced down an embankment by the incident, and another vehicle also was hit. The driver of the semi and the pickup driver were taken to a hospital with moderate to minor injuries, Trulove said.

Several vehicles were struck by pipes — likely drilling or gasoline pipes — which were about 50 feet long. The crash took out about 500 feet of guard rail.

U.S. 6 over Loveland Pass also was closed Tuesday night by visibility restrictions because of snow, blowing snow and fog. The pass would be a way to bypass the tunnel closure, if it were open.

East of the tunnel along the I-70 corridor, U.S. 40 over Berthoud Pass also was closed Tuesday night by a multi-vehicle crash about 5 miles west of Empire. Berthoud Pass reopened at about 9:30 p.m., CDOT said.

Kieran Nicholson covers breaking news for The Denver Post. He started at the Post in 1986, at the old building on 15th and California streets. Nicholson has covered a variety of beats including suburbs, courts, crime and general assignment.

A lead engineer responsible for a pedestrian bridge that collapsed near Miami left a voicemail message for a state transportation official two days before the crash warning of "some cracking," state officials said Friday night.